It is normal to experience some redness, swelling and itching around the incision line but since this rash is more than 10 years old, it is not normal to have itching around that area. Skin conditions like dermatitis, eczema and atopic dermatitis are important possibilities which need evaluation.
I suggest you to get a biopsy of the skin to confirm the diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.